Abstract

Seagrass beds and their associated species communities play key roles in coastal ecosystems. The importance of the ecological functions provided by eelgrass (Zostera marina) and macroinfauna are well understood; however, the spatial variation and linkage of the two are much less known. Here, we performed large-scale field surveys across three biogeographic regions in Atlantic Canada along the coasts of New Brunswick, Nova Scotia, and Newfoundland. First, we examined variation in eelgrass bed structure (shoot density, canopy height, biomass) and environmental parameters (tissue nitrogen and carbon, sediment organic content, microphytobenthos and annual algae) at 19 sites across the 3 regions. Next, we examined the variation in macroinfauna community composition and summary measures (species richness, diversity, total abundance, and biomass). We then linked the eelgrass bed structure and environmental variables to the macroinfauna community to determine what best explained observed patterns. Our results indicate that eelgrass bed structure and most environmental parameters varied at the site level, whereas most variation in the macroinfauna community was explained by region. Furthermore, the abundance of microphytobenthos was the best predictor of the macroinfauna community. We suggest that in moving forward with protecting and managing eelgrass habitats, eelgrass bed structure should be assessed on a site-by-site basis; however, benthic productivity (microphytobenthos) may be a useful tool in evaluating macroinfauna and ecosystem health on a region-scale.

Notes

Acknowledgements

We thank J.S. McCain, M. Namba, K. Wilson, A. Dixon, D. Baker, and T. Harington for support during the field surveys and A. Chan for help in the lab. This work was funded by a National Science and Engineering Research Council (NSERC) Discovery grant to HKL.

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